The formation of ice on aircraft wings can be a severe problem. Ice tends to form from condensation on the leading edge of the wing. The presence of ice changes the geometry of the wing, reduces the lift forces generated by the wing and increases drag. Additionally, ice increases the weight of the wing, thus, compromising the wing's structural integrity.
Two types of ice protection systems, a de-ice system and anti-ice system, are used to reduce the accumulation of ice on aircraft wings. A de-ice system allows solid ice to form on the wing, but removes the ice before it accumulates to a dangerous shape or amount. The accumulating ice is peeled from the wing by the de-ice system and is blown off the wing by passing air. An anti-ice system does not allow solid ice to even form on the wing, thus, only condensate water is formed on the wing and the water is also blown off by the passing air.
Anti-ice systems usually consume large amounts of aircraft power. A typical anti-ice system is an electric heater including a generator of electric power and a series of resistance elements built into the wing structure. This system consumes considerable electric power. A hot bleed air anti-ice system is also used widely. The hot bleed air extracted from the aircraft engine is discharged into the wing structure in order to maintain the temperature of the wing surface above the freezing point and thereby prevent ice from forming. This bleed air anti-ice system does not require electrical power, but extracting bleed air from the engine causes power loss affecting the engine thrust. In either case, a significant amount of power is required for anti-ice systems as compared to de-ice systems. As a result, to maximize aircraft power efficiency, the use of anti-ice systems must be minimized.
Various types of de-ice systems are known. A typical system is a bleed air boot system utilizing bleed air to inflate rubber boots installed on the wing's leading edge. Bleed air is required just to inflate the boots and to remove the ice, so the required amount of air is much less than the hot air anti-ice systems. This device causes less power loss than the hot bleed air anti-ice system. One alternative de-ice system is an electromagnetic expulsion de-ice system. This system removes ice by the impact of electric coils installed in the wing structure. This system requires much less electric power than the electric heater anti-ice system. In either system described above, de-ice systems require much less power than anti-ice systems.
Aircraft wings have been designed that use a combination of de-ice and anti-ice systems in order to minimize the amount of power taken from other systems within the aircraft. Typically, the anti-ice system is configured at an inboard area, adjacent to the fuselage, wrapping around the leading edge of the wing. This prevents ice chunks forming on the wing that could detach and contact and/or enter the aircraft engine and cause destructive results. The remainder (outboard area) of the leading edge of the wing is configured with a de-ice system, wrapping around the leading edge of the wing. However, this combination system design still utilizes a great deal of energy. What is desired is an even more efficient system that prevents the damaging effects of aircraft wing ice.